Novel Rare Earth Near-infrared Fluorescent Probes for in vivo Multiplexed Imaging

Fluorescence encoding and in vivo multiplexed imaging with dual-dimensions of excitation and emission are proposed. A series of second near-infrared(NIR-II, 1000-1700 nm) fluorescent probes [alpha-NaYbF4:8%Tm@NaYbF4@NaYF4 (Yb/Tm), alpha-NaYbF4:2%Er@NaYbF4@NaYF4(Yb/Er) and beta-NaErF4@NaYF4(Er@Y)] were developed for triple-channel in vivo imaging. Among them, Yb/Tm nanoparticles can emit 1640 nm long-wave second near-infrared fluorescence(NIR-II-L, 1500-1900 nm) under 915 nm laser excitation while no fluorescence signal can be detected under 808 nm excitation. Yb/Er can emit NIR-II-L fluorescence at 1532 nm under excitation of 915 nm laser while no fluorescence signal can be detected under 808 nm excitation. In contrast, Er@Y nanoparticles excited by an 808 nm laser can emit NIR-II-L fluorescence at 1525 nm, while a very weak signal can be detected under the excitation of 915 nm. The design of rare earth core-shell nanostructures successfully enhances the fluorescence intensity by 216 times. Under different power density excitations, the nanoparticles still maintain excellent optical properties of independent excitation/emission. Based on the unique optical properties of these nanoparticles, optical encoding and in vivo high-resolution detection with three channels have been achieved, providing new tools and solutions for optical information storage and in vivo multiplexed analysis.